This invention relates to an electric utility meter including a detachable anti-static plastic cover and more particularly to such a cover having an integral contact positioned for connection with the meter chassis by assembly of the cover to the meter.
In electric utility metering, one type of meter often used is a kilowatt demand meter of the type including an elongated or needle type pointer that is movable over a wide arcuate space at the front of the meter relative to a dial having watt demand scale markings. The demand meters are of two general types, one includes a mechanical register type and the other includes the thermal type of demand meter. Illustrative examples of the former type are described in U.S. Pat. Nos. 3,136,947 and 3,207,985. An example of a thermal demand meter is described in U.S. Pat. No. 3,133,247. The aforementioned type of meters are housed in watthour meter type enclosures including a base carrying a meter chassis including the metering movement and a cup-shaped transparent cover detachably mounted to the meter base. Meter covers made of glass are more commonly used, however covers made of plastic are increasing in use. An example of a plastic meter cover capable of being adapted for use with demand meters is disclosed in U.S. Pat. No. 3,846,677 issued Nov. 5, 1974 and assigned to the assignee of this invention. The plastic covers offer an advantage over glass covers in being more resistant to impact and breakage.
As has been sometimes observed when demand meters are enclosed with a plastic cover, an accumulation of static electricity develops on the plastic material of the covers. Since the front face of the covers are often in close adjacent relationship to the demand meter pointers, there may be sufficient static electricity to electrostatically produce movement of the meter pointer. Any extraneously produced movement of a meter pointer is to be avoided to prevent unreliable and inaccurate meter readings. Therefore, it is desirable to provide a detachable anti-static plastic meter cover which is simple and inexpensively manufactured and which can be simply used and installed without alteration or interference in the operation of the meter.